PERFORMANCE EVALUATION OF DS-CDMA SYSTEMS ON MULTIPATH PROPAGATION CHANNELS WITH MULTILEVEL SPREADING SEQUENCES AND RAKE RECEIVERS

Performance of small-cell wireless direct sequence code-division multi ple access (DS-CDMA) systems with multilevel spreading sequences is in vestigated. An analytical methodology to evaluate both outage probabil ity and mean bit error probability is presented, and its results are c ompared to those obtained with a semianalytical Monte Carlo based appr oach. Multipath propagation, the exact correlation properties of sprea ding codes, and both the simple correlator and Rake receivers are take n into account in the analysis, which is oriented to asynchronous and synchronous environments. The spreading sequences investigated include the recently introduced multilevel sequences with complex isomorphic mapping, as well as some well-known two-level sequences. The numerical results show the impact of multilevel sequences on system performance , the improvements found in the absence of multiple access interferenc es by using them rather than binary sequences, and the agreement betwe en analytical and semianalytical evaluation.